The abnormality causing open angle glaucoma has not been identified. Physiology studies indicate that glaucoma is caused by an abnormality of aqueous outflow, but the normal channels by which fluid leaves the eye and mechanisms by which intraocular pressure are controlled have not yet been satisfactorily delineated. The objective of the present study is to more satisfactorily define normal channels of aqueous flow and to identify mechanisms controlling flow. The ultimate goal is to obtain information that can be directly applied to identifying the cause of open angle glaucoma with subsequent improved treatment of the disease. The problem is being approached by examination of the anatomy and function of the outflow channels in living and enucleated eyes from monkeys, attempting to identify physiologic, pharmacologic, and mechanical factors which alter aqueous outflow and intraocular pressure. The specific techniques employed include micro-dissections and mechanical manipulation of the aqueous outflow system, in vivo fixation of the outflow system at precisely controlled intraocular pressures, introduction of pharmacologic agents into the eye, and tracer studies. The effects of these experiments are evaluated by measuring intraocular pressure, by measuring flow through aqueous perfusions, and by evaluating the tissues by light microscopy and transmission and scanning electron microscopy.